May 27th, 2014
Abstract:

Analysis of functional magnetic resonance imaging (fMRI) data is becoming ever more computationally demanding as temporal and spatial resolutions improve, and large, publicly available data sets proliferate. Moreover, methodological improvements in the neuroimaging pipeline, such as non-linear spatial normalization, non-parametric permutation tests and Bayesian Markov Chain Monte Carlo approaches, can dramatically increase the computational burden. Despite these challenges, there do not yet exist any fMRI software packages which leverage inexpensive and powerful GPUs to perform these analyses. Here, we therefore present BROCCOLI, a free software package written in OpenCL that can be used for parallel analysis of fMRI data on a large variety of hardware configurations. BROCCOLI has, for example, been tested with an Intel CPU, an Nvidia GPU, and an AMD GPU. These tests show that parallel processing of fMRI data can lead to significantly faster analysis pipelines. This speedup can be achieved on relatively standard hardware, but further speed improvements require only a modest investment in GPU hardware. BROCCOLI (running on a GPU) can perform non-linear spatial normalization to a 1 mm3 brain template in 4–6 s, and run a second level permutation test with 10,000 permutations in about a minute. These non-parametric tests are generally more robust than their parametric counterparts, and can also enable more sophisticated analyses by estimating complicated null distributions. Additionally, BROCCOLI includes support for Bayesian first-level fMRI analysis using a Gibbs sampler. The new software is freely available under GNU GPL3 and can be downloaded from github: https://github.com/wanderine/BROCCOLI.

(A. Eklund, P. Dufort, M. Villani and S. LaConte: *“BROCCOLI: Software for fast fMRI analysis on many-core CPUs and GPUs”*. Front. Neuroinform. 8:24, 2014. [DOI])

Posted in Developer Resources, Research | Tags: fMRI, Libraries, Medical Imaging, Open Source, OpenCL, Papers | 1 Comment

May 27th, 2014
This master’s thesis by Markus Konrad analyzes the potentials of GPGPU on mobile devices such as smartphones or tablets. The question was, if and how the GPU on such devices can be used to speed up certain algorithms especially in the fields of image processing. GPU computing technologies such as OpenCL, OpenGL shaders, and Android RenderScript are assessed in the thesis. The abstract reads as follows:

This thesis studies how certain popular algorithms in the field of image and audio processing can be accelerated on mobile devices by means of parallel execution on their graphics processing unit (GPU). Several technologies with which this can be achieved are compared in terms of possible performance improvements, hardware and software support, as well as limitations of their programming model and functionality. The results of this research are applied in a practical project, consisting of performance improvements for marker detection in an Augmented Reality application for mobile devices.

The PDF is available for download and the source-code for some Android application prototypes is published on github.

Posted in Research | Tags: Android, Dissertations, Image Processing, Mobile Computing, OpenCL, OpenGL, Renderscript | Write a comment

May 27th, 2014
PARALUTION is a library for sparse iterative methods which can be performed on various parallel devices, including multi-core CPU, GPU (CUDA and OpenCL) and Intel Xeon Phi. The new 0.7.0 version provides the following new features:

- Windows support – full windows support for all backends (CUDA, OpenCL, OpenMP)
- Assembling function – new OpenMP parallel assembling function for sparse matrices (includes an update function for time-dependent problems)
- Direct (dense) solvers (for very small problems)
- (Restricted) Additive Schwarz preconditioners
- MATLAB/Octave plug-in

To avoid OpenMP overhead for small sized problems, the library will compute in serial if the size of the matrix/vector is below a pre-defined threshold. Internally, the OpenCL backend has been modified for simplified cross platform compilation.

Posted in Developer Resources | Tags: Libraries, Numerical Algorithms, NVIDIA CUDA, OpenCL, Sparse Linear Systems, Xeon Phi | Write a comment

May 18th, 2014
Join the free webinar on May 20th devoted to accelerating orthorectification, atmospheric correction, and transformations for big data with GPUs. Learn how GPU capabilities can improve time for processing large imagery 50-100 times faster. Amanda O’Connor, a Senior Solutions Engineer at Exelis will walk you through implementation of GPU processing for large imagery datasets, operational use of GPU processing for orthorectification and share benchmarks against desktop algorithms. To register follow this link: https://www2.gotomeeting.com/register/665929994.

Posted in Business, Developer Resources | Tags: Big Data, Defense, Imaging, Webinars | Write a comment

May 15th, 2014
Boost.Compute v0.2 has been released! Boost.Compute is a header-only C++ library for GPGPU and parallel-computing based on OpenCL. It is available on GitHub and instructions for getting started can be found in the documentation. Since version 0.1 (released almost two months ago) new algorithms including unique(), search() and find_end() have been added, along with several bug fixes. See the project page on GitHub for more information: https://github.com/kylelutz/compute

Posted in Developer Resources | Tags: Libraries, Open Source, OpenCL | 1 Comment

May 15th, 2014
A new version of the GPU-profiler for CUDA software stack is available at www.lab4241.com. The GPU-profiler is able to deliver per C++ source-code ‘inside’ kernel performance information in a simple, intuitive way, similar to known CPU domain profilers, like Quantify or Valgrind. The new version, GPUPROF version 0.3 (beta), includes improved stability, refined memory tracing, temporal memory analysis, and CUDA API-driver call tracing.

Posted in Developer Resources | Tags: NVIDIA CUDA, Profiling, Tools | Write a comment

May 5th, 2014
Abstract:

Frequent itemset mining (FIM) is a core area for many data mining applications as association rules computation, clustering and correlations, which has been comprehensively studied over the last decades. Furthermore, databases are becoming gradually larger, thus requiring a higher computing power to mine them in reasonable time. At the same time, the improvements in high performance computing platforms are transforming them into massively parallel environments equipped with multi-core processors, such as GPUs. Hence, fully operating these systems to perform itemset mining poses as a challenging and critical problems that addressed by various researcher. We present survey of multi-core and GPU accelerated parallelization of the FIM algorithms.

(Dharmesh Bhalodiya and Chhaya patel: *“Comparative Study of Frequent Itemset Mining Techniques on Graphics Processor”*. International Journal of Engineering Research and Applications 4(4):159-163, April 2014. [PDF])

Posted in Research | Tags: Data Mining, Papers | Write a comment

April 29th, 2014
Abstract :

Spectral unmixing is an important task in remotely sensed hyperspectral data exploitation. The linear mixture model has been widely used to unmix hyperspectral images by identifying a set of pure spectral signatures, called endmembers, and estimating their respective abundances in each pixel of the scene. Several algorithms have been proposed in the recent literature to automatically identify endmembers, even if the original hyperspectral scene does not contain any pure signatures. A popular strategy for endmember identification in highly mixed hyperspectral scenes has been the minimum volume simplex analysis (MVSA), known to be a computationally very expensive algorithm. This algorithm calculates the minimum volume enclosing simplex, as opposed to other algorithms that perform maximum simplex volume analysis (MSVA). The high computational complexity of MVSA, together with its very high memory requirements, has limited its adoption in the hyperspectral imaging community. In this paper we develop several optimizations to the MVSA algorithm. The main computational task of MVSA is the solution of a quadratic optimization problem with equality and inequality constraints, with the inequality constraints being in the order of the number of pixels multiplied by the number of endmembers. As a result, storing and computing the inequality constraint matrix is highly inefficient. The first optimization presented in this paper uses algebra operations in order to reduce the memory requirements of the algorithm. In the second optimization, we use graphics processing units (GPUs) to effectively solve (in parallel) the quadratic optimization problem involved in the computation of MVSA. In the third optimization, we extend the single GPU implementation to a multi-GPU one, developing a hybrid strategy that distributes the computation while taking advantage of GPU accelerators at each node. The presented optimizations are tested in different analysis scenarios (using both synthetic and real hyperspectral data) and shown to provide state-of-the-art results from the viewpoint of unmixing accuracy and computational performance. The speedup achieved using the full GPU cluster compared to the CPU implementation in tenfold in a real hyperspectral image.

(A. Agathos, J. Li, D. Petcu and A. Plaza: *“Multi-GPU Implementation of the Minimum Volume Simplex Analysis Algorithm for Hyperspectral Unmixing”*. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, accepted for publication , 2014. [PDF] )

Posted in Research | Tags: Hyperspectral Imaging, Multi-GPU, MVSA, NVIDIA CUDA, Papers | Write a comment

April 16th, 2014
Abstract:

LDPC decoding process is known as compute intensive. This kind of digital communication applications was recently implemented onto GPU devices for LDPC code performance estimation and/or for real-time measurements. Overall previous studies about LDPC decoding on GPU were based on the implementation of the flooding-based decoding algorithm that provides massive computation parallelism. More efficient layered schedules were proposed in literature because decoder iteration can be split into sub-layer iterations. These schedules seem to badly fit onto GPU devices due to restricted computation parallelism and complex memory access patterns. However, the layered schedules enable the decoding convergence to speed up by two. In this letter, we show that (a) layered schedule can be efficiently implemented onto a GPU device (b) this approach – implemented onto a low-cost GPU device – provides higher throughputs with identical correction performances (BER) compared to previously published results.

(B. Le Gal, C. Jégo and J. Crenne: *“An high-throughput efficiency approach for GPU-based LDPC decoding”*. IEEE Embedded System Letters, March 2014. [DOI])

Posted in Research | Tags: Embedded Systems, LDPC decoding, Papers | Write a comment

April 16th, 2014
The GPU Programming for Molecular Modeling workshop will extend GPU programming techniques to the field of molecular modeling, including subjects such as particle-grid algorithms (electrostatics, molecular surfaces, density maps, and molecular orbitals), particle-particle algorithms with an emphasis on non-bonded force calculations, radial distribution functions in GPU histogramming, single-node multi-GPU algorithms, and GPU clusters. Specific examples utilizing the NAMD and VMD software programs will be introduced and discussed in detail. The workshop is designed for researchers in computational and/or biophysical fields who seek to extend their GPU programming skills to include molecular modeling. Advanced lecture sessions will be followed by extended discussion periods between lecturers and participants and laboratory time in which students will be able to work on their own molecular modeling GPU codes. See workshop website for details and application: http://www.ks.uiuc.edu/Training/Workshop/GPU_Jul2014/

Posted in Events | Tags: Molecular Dynamics, Workshops | Write a comment